To deal with the spatial and temporal aspects of the data set, we have chosen to use two views that show different perspectives on the data.

The map view shows the geographical distribution of the observations while the time line view is used to give an overview over some selected features like the amount of observations over time. The time interval from which the observations in the map view originates is controlled by the time line using a slider. When double clicked the slider spans to allow the selection of a time window. The possibility to change the displayed period of time is essential to understand animal population migrations, since they usually form a periodic (annual) pattern. The evolution of such movement patterns over time is potentially very interesting and insightful.

One of the greatest challenges when dealing with the observations is the spatiotemporal point characteristic of the observations together with their sparseness. Since observations usually do not contain information for identifying specific individuals or groups, the user has to find the patterns. Therefore, a key goal of the concept is to emphasize possible migration movements, i.e. to identify possible routes and to distinguish and track groups of animals. To support understanding movement information hidden in the data set, two visual features are planned. When navigating through time, not only the observations at the currently selected time are shown. Instead, the glyphs on the map are smoothly faded in and out to stay visually present when the next observation shows up. Secondly, spatial clustering for group tracing is supported by displaying a blob with a Gaussian opacity falloff. This should result in a kind of animated observation density map when moving through time.

Apart from the \texttt{MapView} (Figure~\ref{fig:map}), the \texttt{TimelineView} (Figure~\ref{fig:time}) contains an alternative visualization of the different data layers. It is meant to give an overview over the time span the user currently investigates. The 2D visualizations for each data set are stacked below the time slider, representing the corresponding time coordinates on the x-axis. For example a scatter plot showing the latitude against time should be beneficial to see annual north-south migrations.

Another important aspect is the possibility to select possibly aggregated observations in one view, and to highlight the selection in all other views where the data case is depicted. Especially the \texttt{AttributeView} (Figure~\ref{fig:attrlayer}) is intended to give detailed information for the selected observations. Also, further descriptions and pictures of the observed animals that come from external sources like web services are accessible in this view.

Finally, the \texttt{LayerView} (Figure~\ref{fig:attrlayer}) allows the user to control the visibility of entire data sets as well as layers showing additional information, such as political borders or elevation. Also included in this view is a simple dynamic query interface for each data set that is currently being visualized, to allow the user to restrict the data on the screen by meta attributes such as species or similar attributes.

\begin{figure}
\centering
\includegraphics[width=80mm]{map.png}
\caption{A screenshot of the \texttt{MapView} component\label{fig:map}}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=80mm]{time.png}
\caption{A preliminary graphic of the \texttt{TimeLine} component\label{fig:time}}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=48mm]{attrib.png}
\includegraphics[width=33mm]{layer.png}
\caption{A screenshot of the preliminary \texttt{AttributeView} (left) as
well as the preliminary \texttt{LayerView} (right)\label{fig:attrlayer}}
\end{figure}
